U.S. patent number 6,113,567 [Application Number 09/133,986] was granted by the patent office on 2000-09-05 for lacrimal silicone tube with reduced friction.
Invention is credited to Bruce B. Becker.
United States Patent |
6,113,567 |
Becker |
September 5, 2000 |
**Please see images for:
( Certificate of Correction ) ** |
Lacrimal silicone tube with reduced friction
Abstract
Lacrimal tissue inflammation and scarring is minimized when an
ostium formed by balloon dacryocystorhinostomy is stented by a
silicone member having a stent portion which may be treated to
reduce friction between the stent portion and tissue supporting the
lacrimal mucosal surface when the silicone member moves due to
blinking. The stent portion may be treated by plasma deposition of
a vaporized silicone based monomer upon the outer surface of the
silicone member which is covalently bonded to the silicone member
thereby forming a silicone polymer coating which is very smooth and
pit-free. The member has a thin central segment of relatively small
outer diameter, a pair of fat segments of relatively large outer
diameter at opposite ends thereof, and thin end segments connected
to the fat segments. The stent portion is formed from the central
segment and the proximate end portions of the fat segments. The
member is inserted in the lacrimal system, by threading each end
segment from the eye through a respective punctum, a canaliculus,
the lacrimal sac and the ostium into the nasal cavity. The member
is pulled down the nasal cavity by grasping the thin end segments
while pulling the fat segments in the opposite direction less
forcefully to stretch and thereby reduce the thickness of the fat
segments so that they more easily move through the lacrimal system.
After the stent portion is brought into place, the untreated
portions of the member are severed.
Inventors: |
Becker; Bruce B. (Hidden Hills,
CA) |
Family
ID: |
24186153 |
Appl.
No.: |
09/133,986 |
Filed: |
August 13, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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547792 |
Oct 25, 1995 |
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Current U.S.
Class: |
604/8; 427/489;
427/491; 604/264; 604/265 |
Current CPC
Class: |
A61F
9/00772 (20130101); A61L 31/06 (20130101); A61L
31/06 (20130101); C08L 83/04 (20130101) |
Current International
Class: |
A61F
9/007 (20060101); A61L 31/06 (20060101); A61L
31/04 (20060101); A61M 005/00 () |
Field of
Search: |
;604/8-10,28,500,264,265,523,285,289,290,294,175,101 ;128/898
;623/11,12,66 ;401/49
;427/2.1,2.12,2.24,2.25,2.28,2.3,574,578,579,583,489,491 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: McDermott; Corrine
Attorney, Agent or Firm: Trexler, Bushnell, Giangiorgi &
Blackstone, Ltd.
Parent Case Text
This application is a continuing application of Ser. No.
08/547,792, filed on Oct. 25, 1995, now abandoned.
Claims
The invention claimed is a follows:
1. A lacrimal stent apparatus adapted to be inserted in an ostium
formed between a patient's lacrimal sac and nasal cavity, said
stent apparatus comprising:
an elongated silicone member comprising a central segment having an
outer diameter, a pair of non-inflatable middle segments at
opposite ends of said central segment, each said middle segment
having an outer diameter which is greater than said outer diameter
of said central segment, and a pair of end segments at distal ends
of the respective middle segments, each said end segment having an
outer diameter which is lesser than said outer diameter of said
middle segments and having a length which is greater than the
length of said central segment, said central segment and the
proximate ends of said middle segments forming a stent portion.
2. The lacrimal stent apparatus as defined in claim 1, further
including a tapered surface between each of said segments and said
middle segments.
3. The lacrimal stent apparatus as defined in claim 1, wherein said
silicone member is a tube.
4. A lacrimal stent apparatus adapted to be inserted in an ostium
formed between a patient's lacrimal sac and nasal cavity, said
stent apparatus comprising:
an elongated silicone member comprising a central segment having an
outer diameter, a pair of middle segments at opposite ends of said
central segment, each said middle segment having an outer diameter
which is greater than said outer diameter of said central segment,
and a pair of end segments at distal ends of the respective middle
segments, each said end segment having an outer diameter which is
lesser than said outer diameter of said middle segments and having
a length which is greater than the length of said central segment,
said central segment and the proximate ends of said middle segments
forming a stent portion, said stent portion being of such length
that said stent portion is adapted to extend from said nasal cavity
through said ostium, said lacrimal sac, one of the patient's
canaliculi, and through one of the patient's puncta, form a loop
over the eye, and extend through the other of the patient's puncta,
the patient's other canaliculus, said lacrimal sac, and said ostium
into said nasal cavity, with said central segment positioned in
said loop.
5. A lacrimal stent apparatus as defined in claim 4, wherein said
stent portion having a surface which is treated to reduce friction
between said stent portion and tissue when said stent portion moves
during blinking, whereby lacrimal tissue inflammation and scarring
is minimized.
6. The lacrimal stent apparatus as defined in claim 5, wherein said
stent portion is treated with a plasma surface treatment.
7. The lacrimal stent apparatus as defined in claim 6, wherein said
plasma surface treatment leaves a pit-free polymerized smooth
surface.
8. The lacrimal stent apparatus as defined in claim 6, wherein said
plasma surface treatment comprises vapor deposition of silicone
based monomer which covalently bonds to said stent portion to form
a pit-free polymerized smooth surface.
9. The lacrimal stent apparatus as defined in claim 4, further
including a tapered surface between each of said end segments and
said middle segments.
10. The lacrimal stent apparatus as defined in claim 4, wherein
said silicone member is a tube.
11. A lacrimal stent apparatus adapted to be inserted in an ostium
formed between a patient's lacrimal sac and nasal cavity, said
stent apparatus comprising:
an elongated silicone member comprising a central segment having an
outer diameter, a pair of middle segments at opposite ends of said
central segment, each said middle segment having an outer diameter
which is greater than said outer diameter of said central segment,
and a pair of end segments at distal ends of the respective middle
segments, each said end segment having an outer diameter which is
lesser than said outer diameter of said middle segments and having
a length which is greater than the length of said central segment,
said central segment and the proximate ends of said middle segments
forming a stent portion, said stent portion having a surface which
is treated to reduce friction between said stent portion and tissue
when said stent portion moves during blinking, whereby lacrimal
tissue inflammation and scarring is minimized.
12. The lacrimal stent apparatus as defined in claim 2, wherein
said stent portion is treated with a plasma surface treatment.
13. The lacrimal stent apparatus as defined in claim 3, wherein
said plasma surface treatment leaves a pit-free polymerized smooth
surface.
14. The lacrimal stent apparatus as defined in claim 3, wherein
said plasma surface treatment comprises vapor deposition of
silicone based monomer which covalently bonds to said portion to
form a pit-free polymerized smooth surface.
15. A method of inserting a silicone stent in an ostium between a
patient's
lacrimal sac and nasal cavity, comprising the steps of:
providing an elongated silicone member having a central segment
having an outer diameter, a pair of middle segments at opposite
ends of said central segment, each said middle segment having an
outer diameter which is greater than said outer diameter of said
central segment, and a pair of end segments at distal ends of the
respective middle segments, each said end segment having an outer
diameter which is lesser than said outer diameter of said middle
segments and having a length which is greater than the length of
said central segment, said central segment and the proximate ends
of said middle segments forming said silicone stent;
threading an end of said silicone member through a punctum and
canaliculus from the patient's eye, into and through said lacrimal
sac and the ostium, and into the nasal cavity;
grasping said silicone member within the nasal cavity;
pulling said silicone member down the nasal cavity and out a
nostril to position said silicone stent in the punctum,
canaliculus, lacrimal sac and ostium; and
cutting off the remaining portions of said silicone member to leave
only said silicone stent in the punctum, canaliculus, lacrimal sac,
and the ostium, extending into the nasal cavity.
16. The method as defined in claim 8, wherein said stent has a
surface which is treated to reduce friction between said stent and
tissue when said stent moves during blinking.
17. The method as defined in claim 8, wherein said threading step
further includes threading the other end of said silicone member
through a second punctum and canaliculus from the patient's eye,
into and through the lacrimal sac and the ostium, and into the
nasal cavity; and
wherein said cutting off step comprises cutting off both ends of
said silicone member after said ends emerge from the ostium into
the nasal cavity to leave said stent therein.
18. The method as defined in claim 10, wherein said pulling step
comprises pulling both said end segments down the nasal cavity by
grasping said end segments while pulling less forcefully on said
middle segments in the opposite direction to stretch and
effectively reduce the diameter of said middle segments allowing
said silicone member to be pulled into position and then grasping
said middle segments in the nasal cavity and pulling said stent
into position extending from nasal cavity through the ostium, the
lacrimal sac, one of the canaliculi, one of the puncta, the other
of the puncta, the other of the canaliculi, the lacrimal sac, and
the ostium back to the nasal cavity.
19. The method as defined in claim 8, wherein said silicone member
is a tube.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to lacrimal silicone tubes and a method of
inserting the same, and more particularly, to lacrimal silicone
tubes which are treated to reduce the friction between the tube and
the supporting tissue.
2. Description of the Prior Art
Tears bathe the surface of the eye and then drain into puncta and
canaliculi on the medial upper and lower lids. The tears flow from
the canaliculi into the lacrimal sac down the nasolacrimal duct
into the nose.
The nasolacrimal duct can become obstructed either congenitally or
by an acquired obstruction in adulthood. When the nasolacrimal duct
becomes obstructed, tears can no longer drain from the surface of
the eye through the lacrimal system into the nose. The tears
therefore well up over the eyes and spill over the lids onto the
face and the patient has to constantly dab the eyes with a tissue.
In addition, tears stagnate in the lacrimal sac which allows
bacteria to multiply. The lacrimal sac then becomes infected
(dacryocystitis). Dacryocystitis causes the lacrimal sac to become
swollen, red, and painful. Pus exudes from the lacrimal sac through
the canaliculi onto the eye and results in purulent material
constantly covering the eye. In time, the dacryocystitis does not
respond to antibiotics and surgery becomes necessary.
Dacryocystorhinostomy (DCR) is the surgery used to correct
nasolacrimal duct obstruction. In a DCR a new opening (ostium) is
created between the lacrimal sac and the nose. This allows tears to
flow from the lacrimal sac through the DCR ostium into the nose. An
open or incisional DCR requires an incision on the side of the
nose. In an open DCR, a large DCR ostium is created by making a 17
mm, plus opening in mucosa and bone. This procedure has significant
morbidity, a prolonged recovery, and the threat of scarring and
hemorrhage. In contrast, a balloon DCR has much less morbidity, no
incision, and a quick recovery. The balloon DCR ostium is smaller
(5 mm.) Than that of an open DCR. Because the balloon DCR ostium is
only 5 mm. in diameter, a stent is required to keep the DCR ostium
open after surgery. Otherwise, postoperative inflammation and
scarring may cause it to close.
A silicone tube is typically used to stent the ostium. The tube has
metal probes at each end and may be inserted by pulling one probe
and tube end through a punctum, a canaliculus, the lacrimal sac,
and the ostium into the nasal cavity. The opposite end of the tube
and its attached probe is then brought through the opposing punctum
and canaliculus, the lacrimal sac, and the ostium into the nasal
cavity. The probes are then grasped in the nasal cavity and brought
down the nose and out the external naris, pulling the tube into
position to stent the ostium, puncta, canaliculi and lacrimal sac.
The tube is left in place as a stent for six months.
It has been found, however, that silicone tube stents induce
lacrimal tissue reaction and inflammation. The inflammation lead,
in time, to increased scar contraction around the ostium. Although
this problem has existed for many years, no one has discovered the
cause of this tissue reaction and inflammation, and no effective
solutions have been suggested by the prior art.
Various balloon dilation catheters and methods using them are shown
in U.S. Pat. No. 5,169,386. As stated at col. 3, lines 47-51, and
col. 9, line 61, col. 10, line 2, it is desirable for the catheter
to include a lubricous coating to facilitate insertion of the
catheter into the lacrimal system. The coating may be a silicone
coating bonded to the catheter or may be a topical coating of
silicone oil. It is also suggested at col. 13, lines 62-65, that
the necks of the balloon be plasma etched. The patent discusses
prior art use of a silicone tube stent in an attempt to maintain
patency of the ostium (col. 1, lines 61-64) and prior art use of a
balloon catheter as a stent with the inflated balloon used to
retain the stent in place (col. 2, lines 4-13).
The prior art teaches that stents used for other purposes can be
coated. Medi-tech Boston Scientific Corporation sells ureteral
stents which are coated with "Glidex" coating. This coating is said
to produce a hydrophilic surface at least eight times more slippery
than an uncoated surface for reducing buckling during advancement,
for facilitating crossing of tight strictures and for easing
negotiation of difficult curves and advancement through
stone-obstructed tracts.
Kurihashi, Opthalmologica, 1993 No. 206, pp. 57-68, teaches
recanalization of the lacrimal passage with silicone tubing which
consists of three pieces: a thinner central segment joined to two
thicker outer segments with sealed distal ends. The tubing extends
through the upper and lower canaliculi and the nasolacrimal
duct.
SUMMARY OF THE INVENTION
According to the invention, it has been discovered that the
lacrimal tissue reaction and inflammation is caused by movement of
the silicone stent and the friction between the stent and the
supporting lacrimal tissue.
Microscopic examination of the surface of the silicone tube reveals
that it is pitted, and it is believed that this pitted surface
contributes to the friction when there is relative movement between
the stent and the lacrimal tissue. This relative movement is caused
by blinking. When the eyelid closes during blinking, the silicone
tube is forced further into the nose. When the lid opens, the tube
is pulled back to its original position in the lacrimal system.
With each blink, the tube moves back and forth across the lacrimal
mucosal surface, generating friction and increasing tissue
inflammation. During the six months the tube is left in place, the
patient blinks tens of thousands of times. The friction between the
tube and the lacrimal mucosa is therefore a major factor in
lacrimal tissue reaction and inflammation.
It is a principle of the invention that this friction can be
reduced by treating the surface of the stent to reduce friction. In
particular, the friction is reduced by coating the surface with a
plasma polymerizate of silicone. The coating is applied in a
process in which a vaporized silicone monomer in a glow zone is
deposited and covalently bonded to the silicone tube forming a
silicone polymer surface.
This surface is much smoother than the surface of an untreated
silicone tube and is substantially pit-free. As a result, lacrimal
tissue reaction, inflammation and scarring are reduced. The ostium
is larger after stent removal, and closure of the ostium is less
likely. Corticosteroids are normally used before tube insertion and
after tube removal to minimize tissue inflammation and scarring.
When the plasma coated stent of the invention is used, the use of
corticosteroids may be reduced.
In addition, plasma coated stents of the invention reduce the
possibility of canalicular narrowing.
Because the plasma deposited coating makes the silicone tube more
rigid, it is more difficult to pull the tube through the relatively
small diameter canaliculi. When the tube is inserted in the
lacrimal system, it is pulled by the surgeon. This stretches the
tube and effectively reduces its diameter. Because a tube upon
which the plasma coating has been deposited is more rigid, its
diameter cannot be reduced sufficiently by stretching. As a result,
an attempt to pull it into place will cause the small diameter end
of the tube to snap off. To solve this problem, the plasma
deposited coating is applied only to the portion of the silicone
tube which will remain in the lacrimal system as a stent. The
structure of the silicone tube is also modified to have a
relatively short "thin" central segment of relatively small outer
diameter, a pair of "fat" segments of relatively large outer
diameter at opposite ends of the central segment and a pair of
"thin" end segments of relatively small outer diameter at the
distal ends of the respective fat segments. The thin end segments
facilitate threading the silicone tube through the lacrimal
system.
The treated stent portion, which comprises all of the central
segment and the proximate ends of the fat segments, is the only
part of the silicone tube treated with the plasma deposited
silicone polymer coating. When the silicone tube is inserted in the
lacrimal system, the thin end segments are grasped in the nose and
used to pull the untreated fat segment portions into place. As the
surgeon pulls the thin end segments down the nose, he also pulls
less forcefully in the opposite direction on the fat segments. This
stretches and reduces the diameter of the untreated portions of the
fat segments and allows them to be pulled through the small
diameter canaliculi and then the lacrimal sac and ostium into the
nose. If the fat segments had not been stretched with their
diameters reduced, the thin end segments would have snapped off as
the fat segments entered the canaliculi. The untreated fat segment
portions are then grasped in the nose, and the more rigid treated
fat segment portions are pulled through the canaliculi, lacrimal
sac, and ostium extending into the nose. The fat segments are
sufficiently strong, that they will not snap off when so
pulled.
In the method of inserting the silicone stent, the end segments are
threaded through a respective punctum and canaliculus, through the
lacrimal sac, and the ostium into the nasal cavity. First the thin
end segments and then the fat segments within the nasal cavity are
grasped and pulled down the nasal cavity and out the nostril to
position the treated stent portion in the puncta and canaliculi,
lacrimal sac, and ostium, extending into the nose. After the tube
is in place, most of it is cut off in the nose. The stent portion
of the tube, which remains in the lacrimal system, is entirely
treated and coated with the plasma deposited silicone polymer
coating. The lacrimal mucosa will contact only a treated surface of
the tube.
When the tube according to the invention is removed six months
after surgery, a dramatic difference can be observed in the ostium
when compared to the use of standard, untreated silicone tubing. A
larger diameter ostium is achieved, and the patency rate is
increased.
BRIEF DESCRIPTION OF THE DRAWINGS
A clearer understanding of the invention will be apparent from the
following description and drawings wherein:
FIG. 1 is a view of a silicone tube according to the invention;
and
FIGS. 2-4 are views illustrating the method of inserting a silicone
tube of the invention.
DETAILED DESCRIPTION
As seen in FIG. 1, which is not drawn to scale, a silicone tube 10
of the invention has a central thin segment 12 of relatively small
outer diameter (0.034 inch), a pair of fat segments 14 and 16 of
relatively large outer diameter (0.050-0.052 inch) at opposite ends
of central segment 12 and a pair of thin end segments 18 and 20 of
relatively small outer diameter (0.034 inch) at the distal ends of
fat segments 14 and 16. Central segment 12 is 13 mm. long; fat
segments 14 and 16 are 15 cm. long; and end segments 18 and 20 are
7 cm. in length. The inner diameter of all segments is 0.016 inch.
The transitions between segments are smoothly tapered.
A stent portion 22 comprises all of central segment 12 and the
proximate end portions 24 and 26 of fat segments 14 and 16. Stent
portion 22, which is 10 cm. in length, is the only part of silicone
tube 10 which has been treated to reduce the friction between the
tube and lacrimal tissue. The treatment, which provides a smooth,
pit-free outer surface to stent portion 22 involves plasma
deposition of vaporized silicone based monomer onto the outer
silicone surface of stent portion 22. As the silicone monomer is
deposited it is covalently bonded to the silicone surface of
silicone tube 10 forming a silicone polymer coating which is very
smooth and pit-free. Stent portion 22 will have very low friction
when it moves relative to lacrimal tissue, as when a patient
blinks.
The process for plasma polymerizing a coating onto the surface of
the silicone tube 10 is the process shown in U.S. Pat. Nos.
4,824,444 and 4,806,246, which are incorporated therein by
reference. Briefly, this process involves moving the silicone tube
10, suitably masked to expose only stent portion 22, through an
energy-intensive glow zone in a region between external electrodes
of an R.F. capacitively coupled tubular reactor. A silicone based
monomer is vaporized and fed into the tubular reactor. The result
is the deposition of a silicone plasma polymerizate coating on the
surface of stent portion 22.
The method of inserting stent portion 22 is illustrated in FIGS.
2-4, which are not drawn to scale. In FIG. 2, silicone tube 10 is
shown partially threaded through the lacrimal system. End segment
18, the relatively small outer diameter of which has eased the
threading of tube 10, with an attached rigid probe 19 has been
threaded from eye 48 through punctum 28, upper canaliculus 30,
lacrimal sac 32 (above nasolacrimal duct 34), and ostium 36 (opened
by balloon DCR) into the nasal cavity 38. The other end segment 20
with another attached rigid probe 21 is threaded from eye 48
through punctum 40, lower canaliculus 42, lacrimal sac 32 and
ostium 36 into the nasal cavity. This leaves a loop 44 with an apex
including stent portion 22 and central segment 12. The surgeon
applies pulling force at the left (nasal cavity) end of thin end
segments 18 and 20 and a smaller pulling force at the apex 44 of
silicone tube 10 to apply sufficient tension to tube 10 that fat
segments 14 and 16 are stretched and made thinner to more easily be
pulled through the puncta, canaliculi and ostium.
As seen in FIG. 3, silicone tube has been fully inserted in the
lacrimal system. End segments 18 and 20 with attached probes 19 and
21 extend out the nostril 46. Stent portion 22 is in stenting
position, extending from the nasal cavity, ostium 36, through
lacrimal sac 32, through lower canaliculus 42, through punctum 40
with central segment 12 looping over the eye 48, back through
punctum 28, upper canaliculus 30, lacrimal sac 32, and ostium 36
into the nasal cavity 38. It will be observed that only stent
portion 22 is now in the lacrimal system.
With treated stent portion 22 in place in the lacrimal system, the
free ends of silicone tube 10 are cut off in nasal cavity 38 at the
point on fat segments 14 and 16 where stent portion 22 begins and
ends. When the cut-off ends are removed, as shown in FIG. 4, only
treated stent portion 22 remains in the lacrimal system where it
acts as a stent for the ostium, the canaliculi and the puncta.
Because stent portion 22 has been treated to reduce friction
between it and the lacrimal tissue, tissue reaction, inflammation
and scarring are greatly reduced. Stent portion 22 does not seal
ostium 36, canaliculi 30 and 42, and puncta 28 and 40, but allows
the flow of tears from the eye through puncta 28 and 40 and ostium
36 into nasal cavity 38. This is particularly the case when a blink
causes fluid pressure forcing the tears to flow along the outside
of stent portion 22.
After stent portion 22 is left in place for six months, it is
removed. There is a dramatic improvement in the condition of the
ostium when compared with its condition after six months of use
with a standard silicone tube which has not been treated according
to the invention to reduce friction. The ostium has a larger
diameter; there is less scarring and inflammation and the patency
rate is increased.
It should be understood that the foregoing description of the
invention is intended merely to be illustrative and other
modifications, embodiments and equivalents may be apparent to those
skilled in the art without departing from the spirit and scope of
the invention.
* * * * *